devise_token_auth 1.1.0 installation fails with "undefined method 'devise' for User"

When posting issues, please include the following information to speed up the troubleshooting process:

* **Version**: 1.1.0
* **Rails Version**: 5.2.3
* **Rails Stacktrace**:
```
rake aborted!
NoMethodError: undefined method `devise' for User (call 'User.connection' to establish a connection):Class
/app/models/user.rb:8:in `include'
/app/models/user.rb:8:in `'
/app/models/user.rb:3:in `'
/config/routes.rb:2:in `block in '
/config/routes.rb:1:in `'
/config/environment.rb:5:in `'
Tasks: TOP => db:migrate => db:load_config => environment
(See full trace by running task with --trace)
```

Given the current installation settings in the documentation, installation fails in a brand new rails project.

Reproduce the documented installation in a new Rails 5.2.3 project and inspect app/models/user.rb together with config/routes.rb. Compare the current installation settings in the documentation, then verify that rake db:migrate completes without the undefined devise method error.

Written by the indexing model from the issue text.